At a news conference at Mattapan Station, Governor Baker, Mayor Walsh, and MBTA representatives announced plans for a new M line, to run from Mattapan to Roslindale Square. The new line, to be completed by 2021, will connect with the new light-rail service on the Needham Line between Forest Hills and a new station on the Riverside Line, where double-track wye will be built. Occasional trips will run through from Ashmont to Riverside, and Mattapan-Boston College trips are also planned. Said the mayor, "Sure, Centre St. and South St. are too narrow for trolleys, but Cummins Hwy is plenty wide enough.